Water-tight plastic component

ABSTRACT

A water-tight plastic component, with a ventilation opening for air exchange between the component interior and the component exterior, and with a gas permeable membrane that covers the ventilation opening to prevent the entry of water into the component interior. The membrane is inserted in a cup-shaped recess disposed in front of the mouth of the ventilation opening, and is clamped at the edge, together with a sealing ring, against the bottom of the recess, in order to achieve a simple assembly. The sealing ring and membrane edge are overlapped by segment tabs that are disposed axially spaced from the bottom of the recess and protrude radially from the cylinder wall of the recess, forming an undercut.

PRIOR ART

The invention is based on a water-tight plastic component, in particulara plastic housing.

In a known plastic component (WO 88/09422), which is embodied as a drivehousing for an electric drive device for adjusting a cover element foran opening in the body of a motor vehicle, such as a window or sunroofor the like, the membrane inserted into the cup-like housing recess issecured by a dish-shaped spring element, which engages in the cylinderwall of the housing recess after the fashion of a so-called speed nutsecuring mechanism. A seal embodied as an O-ring is inserted between themembrane edge and the spring element and is clamped by the springelement together with the membrane edge against an annular supportshoulder that is situated immediately in front of the bottom of thehousing recess.

ADVANTAGES OF THE INVENTION

The water-tight plastic component the has an advantage that the membranewith the sealing ring is simply pressed into the undercuts of thesegment tabs and is reliably secured there while sealing the membrane inrelation to the cylinder wall of the housing recess. As a result, thespring element is no longer necessary, which contributes to a reductionin costs.

Advantageous improvements and updates of the water-tight plasticcomponent are possible by means of the measures taken herein.

According to an advantageous embodiment of the invention, the segmenttabs are offset from one another by equal angles of rotation over theinner circumference of the cylindrical inner wall of the housing recessand are formed directly with the component when it is injection molded.The undercuts of the segment tabs, i.e. the free space between thesegment laps and the bottom or is base of the cup-shaped housing recess,are constituted by means of rotating removal from the mold of an innerdie part of a two-part inner forming die, whose outer die partconcentrically encloses the inner die part and must be previouslywithdrawn from it axially. By means of these measures, the plasticcomponent can be ready made in a single injection molding process andneeds no additional material-removing finishing procedures.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in more detail in the description belowin conjunction with an exemplary embodiment depicted in the drawings.

FIG. 1 shows a detail of a longitudinal section through a plasticcomponent embodied as a housing,

FIG. 2 is a view of the housing detail in the direction of arrow II inFIG. 1,

FIG. 3 is an enlarged depiction of the detail III in FIG. 1,

FIG. 4 shows a detail of a longitudinal section through a two-part innerforming die for injection molding the plastic housing, and

FIG. 5 is a view of the inner forming die in the direction V in FIG. 4.

DESCRIPTION OF THE EXEMPLARY EMBODIMENT

The plastic housing 10, a detail of which is represented in alongitudinal section in FIG. 1, as an example for a general water-tightplastic component, has a ventilation opening 11 for air exchange betweenthe housing interior 12 and the housing exterior 13, and this opening iscovered with a gas permeable membrane 14 to prevent the entry of waterinto the housing interior 12. Coaxial to the ventilation opening 11, astep-shouldered, cup-shaped recess 15 is let into the housing wall 101from the outside and the ventilation opening 11 feeds into its bottom151. An annular rib 16 concentric to the mouth of the feed opening 11 isembodied at the bottom 151 of the recess 15 and maintains a radialdistance a from the outer circumference of the bottom 151 (FIG. 3). Themembrane 14 is placed on this annular rib 16 that protrudes axially fromthe bottom 151 of the recess 15, and by means of a sealing ring 17placed on the edge of the membrane 14, is sealed in a water-tight mannerin relation to the cylinder wall 152 of the recess 15. In an alternativeembodiment, the sealing ring 17 can also be formed onto the membrane 14in one piece with it. The fixing of the membrane 14 with the sealingring 17 is carried out by means of segment tabs 18 that protruderadially from the cylinder wall 152 of the recess 15, spaced axiallyfrom the bottom 151 of the recess 15 to form undercuts 19, and thesetabs overlap the sealing ring 17. The axial spacing of the segment tabs18 from the bottom 151 of the recess 15 is chosen so that it correspondsapproximately to the sum of the axial thicknesses of the membrane 14 andthe sealing ring 17 so that they can be pressed between the annular rib16 and the segment tabs 18 and are reliably fixed there. As shown inFIG. 2, the segment tabs 18 are offset from one another by equalcircumference angles over the circumference of the cylinder wall 152 ofthe recess 15.

The segment tabs 18 are formed directly with the manufacture of theplastic housing 10 that is embodied as an injection molded part, with asimultaneous formation of the ventilation opening 11. A two-part innerforming die 20, a detail of which is shown in FIG. 4, is necessary toembody the ventilation opening 11 during the plastic injection moldingof the housing 10. This two-part inner forming die 20 has an inner diepart 21 and an outer die part 22 coaxially encompassing it. On its oneend face, the inner die part 21 has annular segments 23 extendingradially outward whose dimensions in the plane crosswise to the die axiscorrespond to the dimensions of the radial segment tabs 18 in the recess15 and are distributed over the circumference of the die part 21 inrelation to one another by the same angle of rotation as the segmenttabs 18, and their axial height corresponds to the distance between theundercut face 181 of the segment tabs 18 and the bottom 151 of therecess 15, i.e. the axial depth of the undercut 19. The outer die part22, with its outer circumferential structure, is modeled after thestep-shouldered cylinder wall 152 of the cup-shaped recess 15 and inorder to form the segment tabs 18 in the injection molding process, hasend face recesses 24 that have the same dimensions as the segment tabsand the annular segments 23 flush with them on the inner die part 21.Between these recesses 24 let in from the end face of the outer die part22, claws 25 remain, which pass with positive fit between the annularsegments 23 on the inner die part 21 and end axially flush with theannular segments 23.

In order to mold the recess 15, the two-part inner forming die 20described is inserted into the injection molding form together withanother coaxial inner forming die for molding the ventilation opening11. After the filling of the plastic material, which flows into thehollow spaces remaining between the annular segments 23 on the inner diepart 21 and the recesses 24 axially flush with them in the outer diepart 22, and as a result, forms the segment tabs 18, and after itssolidification, the removal from the mold is carried out, wherein first,the outer die part 22 is withdrawn axially from the inner die part 21and then the removal of the inner die part 21 from the mold is carriedout first by rotation around an angle of rotation, which corresponds tothe spacing angle of the annular segments 23 from one another, and thenby axial withdrawal of the inner die part 21.

The foregoing relates to a preferred exemplary embodiment of theinvention, it being understood that other variants and embodimentsthereof are possible within the spirit and scope of the invention, thelatter being defined by the appended claims.

What is claimed is:
 1. A water-tight plastic component, which comprisesa ventilation opening (11) for air exchange between a component interior(12) and a component exterior (13), a gas permeable membrane (14) thatcovers the ventilation opening (11) to prevent an entry of water intothe component interior (12) through the ventilation opening (11), saidpermeable membrane is inserted in a cup-shaped recess (15) disposed infront of a mouth of the ventilation opening (11), and is clamped at amembrane edge, together with a sealing ring (17), against a bottom (151)of the recess (15), the sealing ring (17) and the membrane edge areoverlapped by segment tabs (18), said segment tabs are disposed at anaxial distance from the bottom (151) of the recess (15) and protruderadially from a cylinder wall (152) of the recess (15), thereby formingundercuts (19).
 2. The component according to claim 1, in which theaxial spacing of the undercut faces (181) of the segment tabs (18)corresponds approximately to a sum of an axial thicknesses of themembrane edge and the sealing ring (17).
 3. The component according toclaim 1, in which the sealing ring and the membrane are formed as aunitary piece.
 4. The component according to claim 1, in which thesegment tabs (18) are offset from one another over the innercircumference of the cylinder wall (152) of the recess (15) by equalangles of rotation and are formed directly with the injection molding ofthe component.
 5. The component according to claim 4, in which theundercuts (19) of the segment tabs (18) are formed by means of rotatingand removal from the mold of an inner die part (21) of a two-part innerforming die (20), whose outer die part (22) concentrically encloses theinner die part (21) and must be previously withdrawn from it axially. 6.The component according to claim 2, in which the sealing ring (17) isformed onto the membrane edge in one piece with the membrane.
 7. Thecomponent according to claim 2, in which the segment tabs (18) areoffset from one another over the inner circumference of the cylinderwall (152) of the recess (15) by equal angles of rotation and are formeddirectly with the injection molding of the component.
 8. The componentaccording to claim 3, in which the segment tabs (18) are offset from oneanother over the inner circumference of the cylinder wall (152) of therecess (15) by equal angles of rotation and are formed directly with theinjection molding of the component.
 9. The component according to claim6, in which the segment tabs (18) are offset from one another over theinner circumference of the cylinder wall (152) of the recess (15) byequal angles of rotation and are formed directly with the injectionmolding of the component.
 10. The component according to claim 7, inwhich the undercuts (19) of the segment tabs (18) are formed by means ofrotating and removal from the mold of an inner die part (21) of atwo-part inner forming die (20), whose outer die part (22)concentrically encloses the inner die part (21) and must be previouslywithdrawn from it axially.
 11. The component according to claim 8, inwhich the undercuts (19) of the segment tabs (18) are formed by means ofrotating and removal from the mold of an inner die part (21) of atwo-part inner forming die (20), whose outer die part (22)concentrically encloses the inner die part (21) and must be previouslywithdrawn from it axially.
 12. The component according to claim 9, inwhich the undercuts (19) of the segment tabs (18) are formed by means ofrotating and removal from the mold of an inner die part (21) of atwo-part inner forming die (20), whose outer die part (22)concentrically encloses the inner die part (21) and must be previouslywithdrawn from it axially.